Email systems are able to sort email messages based upon various rules. For example, a user may establish a rule to sort email messages sent by a particular sender email address into a separate mailbox. The user would initiate the rule creation and interact with a graphical user interface (e.g., dialog box) to enter the sender email address and select or enter that the rule is to apply to messages received from the sender email address. The creation of such a rule involves multiple inputs from the user to create, modify, and confirm the rule. Thereafter, the user can select the separate mailbox to view email messages that originated from that sender email address. The rule created in this example, however, is based only upon the specified sender email address. Should the sender have an additional or new email address, the email system will not sort email messages from the additional or new email address into the separate mailbox.